R.J.
We lived on beaches most of our lives (once literally above the beach, in a converted water tower!).
What my mum would do for the babies (when we lived on a beach sans trees... or she needed to be closer to the water to keep an eye on us older ones) was to dig out the sand to form a pit where it was cooler (aka until she hit the water table). Then she stuck PVC poles in at the corners and bungie corded a blanket to the poles. Nowadays they actually have folding pavillions and beach tents... but she was a MacGyver kind of mum. Even if the instant thing had been available, I'm not sure she'd have used it. Give my mum duct tape and you're in danger. She made a duct tape harness for my brother one year because he was a "runner", and a dog leash she looped through her belt and clipped him to it.